Assigmob to gehebal electbic



Feb. 10, 1931. H. BANY CONTROL SYSTEM Filed Oct. 1, 28

lz 26 3o l 6 Inventor: Herman Bari g,

H i s Attorne g Patented Feb. 10, 1931 when s'rs'rss PATENT caries]lineman Bani; or. Yin molt, rEN'NsYtvAnIn, Assrerion 'ro GENERALELEcrBiC p .PANY; A oonronacrron on NEW YORK CONTROL SYSTEM iApplication 'filed October 1, 1928.- Serial Nos- 309,563;

My invention relates to control systems for alternating current machinesandits objectiszato providexan arrangement whereby an alternatingcurrentmachine is supplied with a-predetermined amount of elicitation whenit-is connected-to a system which is deenergized and is supplied with'alarger amount of excitation. when it is connected to a system which isenergized. I 19 My invention 'is particularly applicable to a controlsystem for. an alternating current generator which is'adapted to beconnected to a lbng transmission line.: VVhenf sucha generator isconnected'to' the-transmission line while it is deenergized the chargingcurrent of the line may-cause the voltage of the generatorlwhen it'issupplied with its normal no load value of excitation to build up toani'excessive value. \Vhen, however, the line is energized,.thegenerator .may be connected to the transmission line and supplied withits normal no load excitation Withoutan excessive voltage occurringacross the gen erator terminals.

I In accordance with my invention I provide an arrangement whereby analternating current machine is supplied with a relatively smallpredetermined value of excitation when the machine is connected to aline which 39 is deenergized and with a relatively large amount ofexcitation when the machine is connected to a line which is energized.

My invention will be better understood from the following descriptiontaken in con nection withthe accompanying drawing which constitutes asingle figure and its scope will be pointed out in the appended claims.

Referring to the accompanying drawing which is a diagram of a controlsystem for an alternating current generator embodying my invention, 1represents an alternator which is arranged to be connected to analternating current circuit 2 by means of a suitable switch 3. Thealternator 1 is provided with a field winding 4 which is adapted to beconnected to an exc'iter 5 by means of a suitable switch 6. As shown inthe drawing the exciter is direct connected to the generator 1. Theswitches 3 and 6 may be controlled in any suitable manner examples ofwhich are well known in the art. l referably theswitch'es are arrangedto be controlled automatically so .tl1at w'hen t he generator-:isstarted the switch 3 is :closed when the generatonreachesapproximately:synchronous speed "and then u the switch 6 isautomaticallyclosed by exciting the generator. r Such automaticrcon- 5 trolarrangements are old a-nd well known in the art.

For controlling the voltage of thegener- 607 ator, 1 after it isconnected to the circuit 2,- I providea voltage regulator 7 of the wellknown Tirrill type 'which :controls a short circuit around'a resistor 8which is connect-- ed in series with-the shunt field winding9 of theexciter. As shown:in the=drawing.- the. regulator '7 includes anA. C.control magnet 10 which isconnected so as to be responsive to thevoltage of the generator 1 and a-D. C. anti-huntingwinding 111 which-isresponsive to the exciter voltage: I 1

12 represents a motor operated-rheostat which is arranged to beconnectedin: series with the exciter 5 and the. generator field winding a whenthe switch 6=is closed.- As 7-, shownin the drawing the rheostat 12 isarranged to be operated to cut resistance out of the generator fieldcircuit when the armature 13 and the field winding 14 of the rheostatmotor are simultaneously energized and to r';; cut resistance into thegenerator-field circuit when the armature l3 and the field winding 15 ofthe rheostat motor are simultaneously energized. For controlling thenormal operation of the motor operated rheostat 12 when the generator 1is supplying current to the circuit 2, a contact making voltmeter 16,which responds to the exciter voltage, is provided: When the excitervoltage tends to exceed a predetermined value the voltmcon ter 16effects the completion of av circuit for the motor of the motor operatedrheostat to decrease the amount of resistance in the generator fieldcircuit. llVhen the exciter volt-- age tends to decrease below apredetermined u.- ralne the voltmeter 16 efiects the compietion of acircuit for the motor of the motor operated rheostat to increase theamount 01 resistance in the generator field circuit.

hen the generator 1 supplies current to a 7" long transmission line, thegenerator at the instant it is placed in operation should be suppliedwith different amounts of excitation depending upon the condition of thetransmission line. If the transmission line is stg zed-a d. he gnerates-is s pp ed with fiinolmalinolnad excitation the voltage of thegenerator may build up to a n egg; cessive value before the motoroperated rheostat 12 caii operate todecreas'e the generator excitationto the desired value. When, however, the transmission line is energizedit is desirable to have the rheostat 12 in its no load voltage positionso that thegeneiamr may be supplied with its no load value of excitationas-soonfas, it: is'placed in operation.

In accordance'wihhmyinvention I: provide a voltage. relay;20;-.which, is responsive to the voltage ofy-the circuit,2 ,="and which; isarrangedtocontrol t-he operation of-motor operated rheostat 12st)that-when the generator. 1 is IlOtdIliQPBl-fitlOIle'thfi rhcostat. isadjusted tea posi-tionfwhereby all; of the resistance of the rheostat isinserted in series with the generatorfield circuit when. the generatoris placed-in operation ata time when the circuit 2 isdeenergizedandwhereby only a por tion of theresistan'ce'of the rheostatis. in sertedin series with the generator fieldeircuitRwheri thegeneratorr islplac'ed in opera.-

tion at a. time when=the circuit-2 is energized. 22 represents .a.master' controlswitch which when closedzpermits-the. motoroperatedrheostat 12 toube controlled'by'the volt age relay 2O andby thevoltmeter 16.

The operation of the arrangement shown inthe drawing iszas follows lhilethe generator 1: is shut down,- the -switch-22-is closed and thecircuit2 islene rgized so that the contacts 2310f. relay 20: areclosed,- a circuit is completed for-the motor operated: rheostat 12 sothat only aportion ofr-the resistance of the. rheostat is. arranged. to.be connected in the generator field circuit: when the switch 6 is closedduring the starting-operation of the generator. This circuit isfrom oneside of a suitable control circuit: through switch 22, contacts.23ofrelay. 20,- auxiliary contacts 24 on switch 3, contacts 25 on rheostat12 which are closed if the rheostat is in a position to insert: morethan a predetermined amount of resistance in thegenerator field circuit,field'winding 14 ofthe rheostat motor, limit switch .26, armaturewinding 130i" the rheostat: motor to the other. side of the controlcircuit. Preferably, the contacts 25 are arranged to be opened wheneverthe rheostat 12 is in the position itnormally occupies when thegenerator is in operation and is supplying substantially no current atnormal voltage. The above traced circuit remains completed until'therheostat 12 is adjusted to the desired position and the contacts25'are If the circuit 2 isdeenergi-zedjso thatcontacts 27 of the relay20 are closed while the enerator is shut down, a circuit is completed orthe motor operated rheostat 12 so that it is adjusted to a positionwhereby all of the resistance thereof is arranged to be connected in thegenerator field circuit when; the generator is placed in operation.:"llhis circuit is iromone side of the control circuit through switch2;, contacts 28 and 29 of the voltmeter 16 which will be closed sincet-hee x citer voltage-willbezero when the generator isshut down,contacts 27 of relay 20, field winding 15 of the rheostat l2, limitswitch 30, which is opened when all of the rheostat has been cut in,armature winding 13 of the rheostat motor to the othen side of: thecontrol circuit.

Therefore, it will be observed that w-henr the generator is shut downthew-rheostat is:

either in a position where all of the.:nesis t-- ance of the rheestatWlll; be connected, in se-" ries with switch 0 the generator field.circuit when the resistance of uhe rheostat will. be connected in serieswith the generator field circuitwhen'.

the switch 6 is closed, That is the rheostat' arm in the arrangementshown 1n the drawing will'elther be 1n.1ts extreme right-hand";

iosition or in or to the leftofthe positionin Y-JlllC'flillQ contacts 25are opened. :1

Vhen the generator. 1 is placed in opera.--

tion it is started from rest and when it reaches .a predetermined'speedthe switches 3 1'00 tomaticahy, 1n any suitable manner examples and 6aresuccessively closed,.pr.eferably'au:-

of which are well known in theart. While the generator is coming upto-speed the exciter "oltage \Vlll be building up since thecontacts 32of the regulator 7 are closed. due

to the fact that the coils of both ofthe magmeter 16 to open itscontacts 28 and 29 and" close its contacts 28 and 33 before the switches3 and 6 are closed a circuit is completed for. armature 13 and fieldwinding 14 of the-rheostat motor to effect a decrease in the amount ofresistance incircuit as soon as the switch is closed. After the switch3' is. closed to connect the generator to the line the regulator 7operates in a, manner wellknown in the art to maintain the'generatorvoltage at the desired value. After the switch 3 closes the position ofthe rheostat' l2'depends upon the position of the voltmeter 16;

If the exciter voltage is too high a circuit is completed for thewindings 13 and 140i therheostat motor, through contacts 28=and 33 isclosed or ina position whereby not more than a predetermined:portion-ofthe and auxiliary contacts 34 on the switch 3 so that the amount ofresistance in the generator field circuit is decreased and, therefore, alower exciter voltage is needed to maintain the desired generatorvoltage. If the exciter voltage is too low a circuit is completed forthe winding 13 and 15 of the rheostat motor through contacts 28 and 29of the voltmeter 16 and the auxiliary contacts 35 so that amount ofresistance in the generator field circuit is increased and, therefore, alarger exciter voltage is needed to maintain the desired generatorvoltage.

While I have, in accordance with the patent statutes, shown anddescribed my invention as applied to a particular system and asembodying various devices diagrammatically indicted, changes andmodifications will be obvious to those skilled in the art and I,therefore, aim in the appended claims to cover all such changes andmodifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In combination, an electric circuit, a generator, a switch forconnecting said generator to said circuit, an exciter for saidgenerator, a rheostat, means for connecting said rheostat in seriesbetween the exciter and the generator field winding, electromagneticmeans arranged when energized to efiect the operation of said rheostatso as to decrease the amount of resistance in circuit, means responsiveto voltage of said circuit, and a control circuit for saidelectromagnetic means controlled by said switch and said voltageresponsive means and said rheostat so that it is completed only when-thevoltage of said electric circuit is above a predetermined value, theswitch is open and more than a predetermined amount of said rheostat isconnected in the generator field circuit.

2. In combination, an electric circuit, a generator, a switch forconnecting said generator to said circuit, an exciter for saidgenerator, a rheostat, means for connecting said rheostat in seriesbetween the exciter and the generator field winding, electromagneticmeans arranged when energized to efiect the operation of said rheostatso as to decrease the amount of resistance in circuit, means responsiveto voltage of said circuit, a control circuit for said electromagneticmeans con trolled by said switch and said voltage responsive means andsaid rheostat so that it is completed only when the voltage of saidelectric circuit is above a predetermined value, the switch is open andmore than a predetermined amount of said rheostat is connected in thegenerator field circuit, another control circuit for saidelectromagnetic means, and means responsive to the voltage of saidexciter for completing said last mentioned control circuit when theexciter voltage exceeds ajpredetermined'value. H V 2 ,3,"In combination;.an electric circuit,-. a

generator, at switch-:for' co'nnecti'ngsaid generatortosaid-circuit,--an exciter tors-aid genenatdr, ahrheostatmeans tor,connecting said rheostat in series between the exciter and thegenerjatonfield winding, means responsive to the Fexciter voltage, meansresponsive to the voltage ofaisaidcircuit, electromagnetic meansarranged when energized t'oyeffect the operation-of said rheostat so asto increasethe amounti-of resistance' thereof in circuit, and.

a control circuit for said last mentionedelectrom'agneticmeanslcoritrolled by said exciter voltage responsivemeans and said load circuit voltage responsive means so that it iscompleted only when the load circuit voltage and exciter voltage arebelow predetermined values.

4. In combination, a generator having a.

generator to said load circuit, and means responsive to the voltage ofsaid load circuit for controlling the adjustment of said rheostat whensaid generator is disconnected from said load circuit.

5. In combination, a generator having a field circuit, an exciter forsupplying current to said field circuit, an adjustable rheostat in saidfield circuit, regulating means responsive to the voltage of saidgenerator for controlling the voltage of said exciter, a load circuit,switching means for connecting said generator to said load circuit,means controlled by said connecting means and the voltage of said loadcircuit for controlling the adjustment of said rheostat in accordancewith the load circuit voltage when said generator is disconnected fromsaid load circuit.

6. In combination, a generator having a field circuit, an exciter forsupplying current to said field circuit, an adjustable rheostat insaidfield circuit, regulating means responsive to the voltage of saidgenerator for controlling the voltage of said exciter, a load circuit,switching means for connecting said generator to said load circuit,means controlled by said connecting means and the voltages of saidexeiter and load circuit for controlling the adjustment of said rheostatin accordance with the load circuit voltage when said generator isdisconnected from said load circuit and in accordance with the excitervoltage when said generator is connected to said load circuit.

7. In combination, a transmission line requiring a relatively largecharging current,

a synchronous" dynamo el'ctiifc in'abhih'w switching means forconncpingsaid machine to said line, an adjustable rheostwt irsflie fieldcircuit (if said machine' and meansmmrolledg by said switching'means andthe voltage -of said line for varying theiposifiio'n df 'saidrhe'o statin acco rdanc' with fih' voltage of 5 said' line wliile'said machineidiscon n'cted from", said line and in accordance the excitation iHERMAMB'A YL

